1. Field of the Invention
The present invention generally relates to a collapsible type radio communication device in which the antenna is built in the interior of the housing, and the upper housing and the lower housing are connected by the hinge part so that they are mutually rotatable.
2. Description of the Related Art
In a collapsible type portable telephone which is a kind of the structure of the portable telephone, the upper housing and the lower housing are connected by the hinge part so that they are mutually rotatable around the hinge part. The collapsible portable telephone is provided so that the upper housing can be opened and closed to the lower housing.
The portable telephone of the collapsible type provides the advantageous features in that the upper housing can be equipped with a large-sized display screen, that the composition when the upper housing is opened makes use of the telephone easy, and that the slim structure when the upper housing is closed to the lower housing is convenient to carry.
In a conventional portable telephone of the collapsible type, the projection type antenna arranged in the lower housing or the projection type antenna arranged in the upper housing is used.
Generally, the helical antenna or the extendable monopole antenna is used as the projection type antenna, and the antenna portion projects from the housing. The projection type antenna provides the advantageous feature in that the antenna gain can be made high in a condition that the user holds the portable telephone by hand.
However, with the projection type antenna, there is the problem that the antenna portion projecting from the telephone housing is obstructive when taking out the portable telephone from the user's pocket on the occasion of use.
On the other hand, as the antenna built in the housing of the collapsible portable telephone, the strip line antenna and the hinge-part built-in type antenna are known. Moreover, the flip-part built-in type antennas, such as the coil-like antenna and the micro strip line antenna, are also known.
Since there is no portion which projects from the housing according to such built-in antennas, the problem like the problem of the projection type antenna does not arise with such built-in antennas.
For example, Japanese Laid-Open Patent Application No. 2003-008320 discloses a collapsible portable telephone which uses the hinge-part built-in type antenna.
In this portable telephone, the hinge-part built-in type antenna is arranged at a position which is adjacent to the hinge part connecting the upper housing and the lower housing, and overlaps the upper part of the flexible wiring board.
FIG. 1 shows the outline composition on the front side of a conventional portable telephone. FIG. 2 shows the outline composition on the back side of the conventional portable telephone.
As shown in FIG. 1 and FIG. 2, the conventional portable telephone 1 is of the collapsible type, and comprises the upper case 2 and the upper cover 11 which attach the display unit, such as the liquid-crystal-display unit, to the upper case surface, the lower cover 4 and the lower case 12 which attach the key operation unit including ten keys, various function keys, etc., to the lower case surface, and the hinge part 3 and the hinge part 5 which connect the upper case 2 and the lower cover 4 to be mutually rotatable around the hinge parts.
By assembling the portable telephone 1, the upper case 2 and the upper cover 11 form the upper housing of the portable telephone 1, and the lower cover 4 and the lower case 12 form the lower housing of the portable telephone 1.
The upper housing circuit board 6 for attaching the various electric parts including the display unit is provided in the upper housing of the portable telephone 1, and the back surface (for the sake of convenience, the surface shown in FIG. 2 will be called the back surface) of the upper housing circuit board 6 is protected by the upper cover 11.
The lower housing circuit board 7 for attaching the various electric parts including the key operation unit is provided in the lower housing of the portable telephone 1, and the back surface (the surface shown in FIG. 2 will be called the back surface) of the lower housing circuit board 7 is protected by the lower cover 4.
The hinge part 3 is formed integrally with the upper case 2, and the hinge part 5 is formed integrally with the lower cover 4. Moreover, the hinge parts are formed integrally with the upper cover 11 and the lower case 12, respectively. The upper cover 11 and the lower case 12 are provided so that they are mutually rotatable around the hinge parts. Therefore, the upper housing and the lower housing are provided so that they are mutually rotatable around the hinge parts.
The flexible wiring board 8 electrically connects the upper housing circuit board 6 and the lower housing circuit board 7 each other, and is arranged to extend from the upper housing circuit board 6 to the lower housing circuit board 7 through the hinge part 5.
The flexible wiring board 8 is formed of a flexible member. In order to accommodate the flexible wiring board 8 in a small space adjacent to the hinge part between the upper and lower housings, the flexible wiring board 8 is arranged in the state where it is wound once or more around the hinge part 5 in the middle of the flexible wiring board 8.
The antenna electric supply part 9 is arranged at the end of the lower housing circuit board 7 near the hinge part 5, generally in the center of the lower housing circuit board 7 along the axial direction of the hinge part.
The antenna 10 is provided at the end of the lower housing adjacent to the hinge part 5. The antenna 10 is formed of a sheet metal, and it is formed in a predetermined form so that sufficient antenna gain may be obtained.
The antenna 10 is arranged in the position contiguous to the flexible wiring board 8 in the lower case 12 so that the electric supply terminal and ground terminal which are prolonged from this antenna 10 may contact the antenna electric supply part 9.
The antenna 10 operates by the operating current supplied through the electric supply terminal from the antenna electric supply part 9 of the lower housing circuit board 7, and functions as an antenna for transmission and reception.
With the progress of the multiple functionality in the recent portable telephones, it is desirable to make the display unit of the upper housing as large as possible, and the key operation unit of the lower housing has restrictions in that it cannot be made much smaller from the viewpoint of operability.
Moreover, in the portable telephone of this kind of collapsible type, since it tends to be bulky when the thickness becomes thick as a whole and the upper housing and the lower housing are put into the pocket etc. in the state where it closed focusing on the hinge part, since the upper housing and lower housings overlap mutually, the slim structure of the portable telephone is desired.
On the other hand, the number of wirings, such as signal wires in the respective circuit boards provided in the upper and lower housings, tend to increase by the multiple functionality of the portable telephones, and adoption of the big drop of size.
Therefore, it is in the tendency for the numbers of wiring, such as signal wiring accommodated in the flexible wiring board formed in order to connect between the circuit boards of the upper and lower housings, to also increase.
Securing the increased number of wirings of this circuit board will bar the slim structure of the portable telephone of the collapsible type. That is, in order to satisfy the demand of thin structure, there are restrictions that width of the flexible wiring board of the securable for the internal space of the circuit board of the upper and lower housings can seldom be enlarged.
Moreover, in order to accommodate much signal wiring, when unavoidable, in order to have to form two or more flexible wiring boards in the space inside the upper and lower housings in piles, the subject that the slim structure of the portable telephone becomes difficult occurs.
FIG. 3 and FIG. 4 show the composition by the side of the surface of the conventional portable telephone in the state where it is folded down, and the back.
FIG. 5 shows the outline composition when removing the lower case in the portable telephone of FIG. 4.
As shown in FIG. 3, in order to accommodate the winding portion in the middle of the flexible wiring board 8 in a small space near the hinge part between the upper and lower housings in the conventional portable telephone 1, there are restrictions that making the width (indicated by the arrow B1 in FIG. 3) of the flexible wiring board 8 in the hinge part axial direction so much large is not allowed.
Moreover, the flexible wiring board 8 needs to be arranged so that it may not interfere with the antenna electric supply part 9 of the lower housing circuit board 7.
As shown in FIG. 4, the antenna 10 is arranged in the position contiguous to the flexible wiring board 8 in the lower case 12 so that the electric supply terminal 13 and the ground terminal 14 which are prolonged from the antenna 10 may contact the antenna electric supply part 9 of the lower housing circuit board 7.
As shown in FIG. 5, the electric parts which affect the antenna property at the time of operation of loudspeaker 15 grade besides the electric parts of the key operation unit are also attached in the lower housing circuit board 7.
The form of the antenna 10 which includes the pieces of metal, such as the copper and the aluminum, makes as small as possible influence which it has on the property of the antenna 10 by the electric parts on the lower housing circuit board 7, and it needs to be constituted so that sufficient antenna gain may be obtained.
Moreover, in consideration of the property of the antenna 10, it is necessary to opt for arrangement of the antenna electric supply part 9 in the lower housing circuit board 7.
As mentioned above, the number of wirings of the wiring circuit board carried in the portable telephone is in the tendency to increase in recent years, so the number of wirings of the flexible wiring board 8 also tends to increase. On the other hand, however, there is also the demand for the slim structure of the portable telephone.
In the conventional portable telephone of the collapsible type, in order to satisfy the demand for the slim structure, the problem in that it is difficult to take a large width of the flexible wiring board that can be provided in the internal space of the wiring circuit boards of the upper and lower housings arises.